PROJECT SUMMARY/ABSTRACT The majority of older Americans live with chronic health conditions, and pain is the most common physical symptom experienced across conditions. Spouses of older adults with chronic pain are caregivers in a broad sense, and often provide assistance with daily activities; however, ongoing exposure to patients? suffering is likely to take a toll on the health and well-being of these caregivers. Moreover, our recent research suggests that older spouses in a close marital relationship are more affected by their partner?s pain than spouses in a less close relationship. This intriguing finding suggests that closeness may be good for the relationship but bad for spouses when patients are in more pain. The proposed project will test for these divergent effects and their longer-term implications in a sample of 144 older adults with chronic low back pain (CLBP), due to the high prevalence and treatment-related costs of this condition in the Medicare population. Patients and caregivers will report on their daily experiences twice per day for 30 days using tablet computers. They will also complete in-person interviews and physical function assessments every 6 months over 2 years. Aim 1 is to examine prospective effects of patients? daily pain experience (severity, interference, catastrophizing) on spousal caregivers? distress (i.e., reactivity) and controlling responses, and divergent effects of daily closeness. We predict that patients? pain experience will have stronger associations with spouses? subsequent distress, and spouses will respond with more solicitousness and pressure, on days of high closeness than on low closeness days. In addition, we predict greater daily closeness will be associated with more marital satisfaction that day, for both partners. Bi-directional and cross-day effects also will be examined in tests of these hypotheses. Aim 2 will use multilevel latent growth curve modeling to link daily caregiver emotional reactivity and controlling responses with longer-term outcomes for both partners. Our prediction is that spouses who are more distressed by patients? pain will have more depressive symptoms over 2 years compared to those who are less distressed. In addition, we expect that patients whose spouse is more controlling in response to patients? pain will have worse physical function, greater disability, and increased health care utilization over 2 years compared to those whose spouse is less controlling. Significance of this study lies in: 1) improved understanding of the impact of late-life pain on spousal caregivers? well-being; 2) identification of longer-term consequences of dynamic, dyadic experiences for both patients and caregivers; and 3) findings that will be used to create a couple-oriented intervention for CLBP in future research. Areas of innovation include a novel conceptualization of relationship closeness that will reveal its advantages and disadvantages for couples living with chronic pain, a focus on older couples, and a study design that will enable strong conclusions regarding temporal sequence of daily experiences and their longer-term consequences.